Insomnia, a disorder in which a person has trouble obtaining high-quality and restorative sleep, can lead to adverse conditions such as obesity, depression, frequent headaches, crankiness, fatigue, poor concentration, and greater risks of diabetes and heart disease. What’s more, medical researchers have recently discovered another problem that insomnia can cause. In 2015, the official journal of the International Association for the Study of Pain (IASP) published the results of a study indicating that insomnia can make people more sensitive to pain. On top of that, the link between insomnia and lower pain tolerance is especially pronounced in patients who suffer from chronic pain. Dr. Borge Sivertsen, a member of the Norwegian Institute of Public Health, oversaw this landmark study, the first formal, large-scale inquiry into the connection between insomnia and pain sensitivity. During this study, more than 10,000 individuals from Norway underwent a cold pressor test. This common experiment requires that a person keep one hand in cold water for 106 seconds or for as long as he or she can stand it ― whichever duration is shorter. Sivertsen’s team also asked all of the participants a detailed series of questions regarding their sleep patterns. The conclusions to be drawn from this intriguing project are clear. About 42 percent of people who suffer from insomnia failed to keep a hand in the water for the entire 106-second count. By contrast, only 31 percent of those without sleeping difficulties were unable to finish the test, and the more intense a person’s case of insomnia happened to be, the less likely he or she was to complete the cold pressor task. In addition, the rate of increased pain sensitivity was more than twice as high among people afflicted with chronic pain and insomnia than it was among people with neither malady. At this time, no complete scientific explanation exists as to why insomnia would lessen pain tolerance. There might be a psychological component to the connection. For instance, an anxiety disorder could be the cause of both conditions. On the other hand, some people might be deficient in a certain neurological chemical, one that facilitates sleep and improves pain endurance.